Emil O W Kirkegaard

The idea would be that this subset would be self-destructively bad at making life choices. If the data holds and is still applicable I don’t know.

Just generally speaking that it's an unusual choice and these are generally made by risk takers. It could be analyzed in datasets by looking at e.g. smoking rates among outbreeders. Some discussion in http://emilkirkegaard.dk/en/?p=6618 

One might choose an outgroup partner as one might choose a tattoo: to declare to the world one does not conform to traditions, which probably formed partly for their health and security benefits. Also, to avoid criticism for ones bad choices from ones partner.

1. A hypothesis: Since everything we think and do is nothing more than an expression of our inherited replicators to an environment, it would stand to reason that all else being equal (environment: time spent together, IQ,…)

2. genetically more similar people will on average be in less conflict than genetically less similar people. I think this is one of the major reasons why people tend to gravitate towards people that are genetically more similar to them